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<h2>ncdump</h2>
<code>ncdump [-c] [-h] [-v <i>var1</i>,...] [-b <i>lang</i>] [-f
<i>lang</i>] [-l <i>len</i>]
          [-n <i>name</i>] [-d <i>f_digits</i>[,<i>d_digits</i>]]
<i>file</i></code><p>
Where:<p>
<ul>
<code>-c</code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   Show the values of
<i>coordinate</i> variables (variables that
          are also dimensions) as well as the declarations of all
          dimensions,  variables,  and  attribute  values.   Data
          values  of non-coordinate variables are not included in
          the output.  This is the most suitable  option  to  use
          for  a  brief  look  at the structure and contents of a
          netCDF file.<p>

<code>-h</code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   Show only the
<i>header</i>
information in the output, that is
          the  declarations  of dimensions, variables, and attributes but no data values for any variables.  The output
          is  identical  to  using  the <code>-c</code> option except
that the
          values of coordinate variables are not  included.   (At
          most one of <code>-c</code> or <code>-h</code> options may be
present.) <p>
<code>-v</code>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
<code><i>var1,...,varn</i></code><br>
<ul>
          The output will include data values for  the  specified
          variables,  in  addition to the declarations of all dimensions, variables, and attributes.  One or more variables  must be specified by name in the comma-delimited
          list following this option.  The list must be a  single
          argument to the command, hence cannot contain blanks or
          other white space characters.  The named variables must
          be  valid  netCDF variables in the input-file.  The default, without this option and in the absence of the
<code>-c</code>
          or  <code>-h</code> options, is to include data values for
<i>all</i> variables in the output.</ul><p>

<code>-b <i>lang</i></code><br>
<ul>
          A brief annotation in the form of a CDL  comment  (text
          beginning  with the characters ``//'') will be included
          in the data section of the output  for  each  `row'  of
          data, to help identify data values for multidimensional
          variables.  If <code><i>lang</i></code> begins with
<code>C</code> or <code>c</code>, then C
          language  conventions will be used (zero-based indices,
          last dimension varying fastest).  If <code><i>lang</i></code> 
begins
with
          <code>F</code>  or  <code>f</code>, then Fortran language
conventions will be
          used  (one-based  indices,  first   dimension   varying
          fastest).   In  either case, the data will be presented
          in the same order; only the  annotations  will  differ.
          This  option  is  useful  for  browsing  through  large
          volumes of multidimensional data. </ul><p>    

<code>-f <i>lang</i></code><p>
<ul>
Full annotations in the form of trailing  CDL  comments
          (text  beginning  with the characters ``//'') for every
          data value (except individual characters  in  character
          arrays)  will be included in the data section.  If
<code><i>lang</i></code>
          begins with <code>C</code> or <code>c</code>,  then  C
language conventions
          will  be used (zero-based indices, last dimension varying
fastest).  If <code><i>lang</i></code> begins with  <code>F</code>  or
<code>f</code>, then
          Fortran  language  conventions  will be used (one-based
          indices, first dimension varying fastest).   In  either
          case,  the  data  will  be presented in the same order;
          only the annotations will differ.  This option  may  be
          useful  for  piping data into other filters, since each
          data value appears on a separate  line,  fully
identified.</ul><p>

<code>-l <i>len</i></code><br>
<ul>
Changes the default maximum line
length (80) used
in
          formatting lists of non-character data values.     </ul><p>

<code>-n <i>name</i></code><br>
<ul>
          CDL requires a name for a netCDF data set, for  use  by
          <a href="ncgen.html"><code>ncgen -b</code></a> 
in generating a default netCDF file name. By
          default, <code>ncdump</code> constructs this name from the
last component  of  the  pathname  of  the input netCDF file by
          stripping off any extension it has.  Use the <code>-n</code> 
option
          to  specify a different name.  Although the output file
          name used by <a href="ncgen.html"><code>ncgen -b</code></a> 
can be specified, it may be wise
          to  have  <code>ncdump</code> change the default name to avoid
inadvertantly overwriting a valuable netCDF file when using
          <code>ncdump</code>, editing the resulting CDL file, and using
<a href="ncgen.html"><code>ncgen
          -b</code></a> to generate a new netCDF file from  the  edited
CDL
file.</ul><p>

<code>-d <i>float_digits</i>[,</i>double_digits</i>]</code><p>
<ul>
Specifies default number of significant digits  to  use
          in  displaying  floating-point or double precision data
          values for variables that don't have a  `C_format'  attribute.   Floating-point  data  will be displayed with
          <code><i>float_digits</i></code> significant digits.  If
<code><i>double_digits</i></code> is
          also   specified,   double-precision   values  will  be
          displayed with that  many  significant  digits.   If  a
          variable has a `C_format' attribute, that overrides any
          specified floating-point default.  In  the  absence  of
          any   <code>-d</code>  specifications,  floating-point  and
double-
          precision data are displayed with 7 and 15  significant
          digits  respectively.  CDL files can be made smaller if
          less precision is required.  If both floating-point and
          double-presision  precisions  are  specified,  the  two
          values must appear separated by a comma (no blanks)  as
          a  single  argument to the command.  If you really want
          every last  bit  of  precision  from  the  netCDF  file
          represented  in the CDL file for all possible floating-
          point values, you will have to  specify  this  with  <code>-d
          9,17</code>.</ul></ul>


<h3>Usage Notes</h3>
<code>ncdump</code> generates an  ASCII  representation  of  a
specified
     netCDF file on standard output.  The ASCII representation is
     in a form called <code>CDL</code> (``network Common Data form
Language'')
     that  can  be  viewed,  edited,  or serve as input to <a
href="ncgen.html"><code>ncgen</code></a>.
     <a href="ncgen.html"><code>ncgen</code></a> is a companion program
that can generate a binary
     netCDF  file from a <code>CDL</code> file.  Hence <a
href="ncgen.html"><code>ncgen</code></a> and <code>ncdump</code> can
be
     used  as  inverses  to  transform  the  data  representation
     between  binary  and ASCII representations.  See <a
href="ncgen.html"><code>ncgen</code></a> for a
     description of CDL and netCDF representations.<p>

<code>ncdump</code> defines a default format used for each type of
netCDF
     data,  but  this can be changed if a `C_format' attribute is
     defined for a netCDF variable.  In this  case,  <code>ncdump</code> 
will
     use  the `C_format' attribute to format each value.  For example,
if floating-point data for the netCDF variable <code>Z</code> is
     known  to  be  accurate to only three significant digits, it
     would be appropriate to use the variable attribute<p>
          <dd><code>Z:C_format = "%.3g"</code><p>
<code>ncdump</code> may also be used as a simple browser for netCDF
data
     files,  to  display  the dimension names and sizes; variable
     names, types, and shapes; attribute names  and  values;  and
     optionally, the values of data for all variables or selected
     variables in a netCDF file.<p>

<h3>Examples</h3>
<ol>
Look at the  structure  of  the  data  in  the  netCDF  file
<code>foo.nc</code>:<p>
<dd><code>ncdump -c foo.nc</code><p>
<li>Produce an annotated CDL version of the structure  and  data
     in  the netCDF file <code>foo.nc</code>, using C-style indexing for
the
     annotations:<p>
<dd><code>ncdump -b c foo.nc > foo.cdl</code><p>
<li>Output data for only the variables <code>uwind</code> and
<code>vwind</code> from
     the  netCDF  file <code>foo.nc</code>, and show the floating-point
data
     with only three significant digits of precision:<p>
<dd><code>ncdump -v uwind,vwind -d 3 foo.nc</code><p>
<li>Produce a fully-annotated (one data value per line)  listing
     of  the data for the variable <code>omega</code>, using Fortran
conventions for indices, and changing the netCDF dataset  name  in
     the resulting CDL file to <code>omega</code>:<p>
<dd><code>ncdump -v omega -f fortran -n omega foo.nc > Z.cdl</code></ol>

